Stem for incandescent lamps and method of making



} v 4 1,62 1927' .1. J. HIGGINS 6 677 STEM FOR INCANDESCENT LAMPS AND METHOD OF MAKING Filed March 25 22 FIG. 1.

INVENTOR JOHN J., HIGGINS ATTORNEY OF EAST- ORANGE, JERSEY," ASSIGNOR T WESTIIFG- JOHN JOSEPH HIGGINfi,

HOUSE LAMPMOOMPANY,

'A CORPORATION OF PENNSYLVANIA.

srnm roa INCANDESCENT LAiurs Ann mn'rnon or Maxine.

' Application filed March 25, 1922. Serial No. 546379.

This invention relates to incandescent lamps and their manufacture and more particularly to the stem used with the type known as the tipless lamp, although my invention may also be employed in a tipped for incandescent lamps lamp.

An object of my'invention is the provision of a method for the manufacture of stems and other electrical devices including a sealed container whereby the cost of their production is reduced.

. in a stem-making Another object of my invention is the provision of a stem fora tipless incandescent lamp comprising a less number of parts than those heretofore used, certain of which parts perform additional functions.

A further object of my. invention is the provision of a stem of rugged construction composed of few parts and made in such a manner that cooling strains 1 and other sources of shrinkage are lessened.

Other objects and advantages of the. invention will be apparent as the description proceeds.

Stems for lamps of the tipless construc-' tion are at present made by placing the flare machine, inserting an inner or exhaust tube therein with the leading-in wires therebetween and, after softening the glass in the usual manner by heat, the flare, the inner tube and the wires are consolidated by the application of clamping jaws or other mechanical pressing means. This method weakens the stem to a consider.- able extent by elongation or flattening the same atthe press by the usual clamping jaws, which also chills the glass, causing severe coolingstrains. With a tipless lamp, the blowing of the necessary small exhaust hole near the press was a source of weakness and shrinkage. v

' With my improved method, the flare, the inner tube and the leading-in placed in a stem-making machine,'and fusion between the tubes caused by the external application of heat andthe internal application of air pressure i. e., after lnserting the inner tube and leading-in wires, gas fires or other suitable heating means, are allowed to act on the small end of the flare and an igtermediate portion of. the, inner tube. When a tipless variety of stem is to be made, and the glass is in a plastic state, the inner tube is prevented from closing up by -means of air pressure applied within the wires are inner tube; preferably in the form of a jet of air. 7 The weld or fusion between the two tubes is formed by the surface tension of the glass when in a plastic state assisted by the pressure of the gas fires, if such are used, acting against the air pressure on the inside of the inner tube. I

The jet of compressed air directed down the inner tube also serves to cause the stem, which has been formed by this method, to c931 from the inside, as well as from the out- Sl e, reducing cooling strains. A slight expansion of the inner tube at the point of fusing isdesirable but not essential and may be regulated by the air jet thus diminishing cooling strains by'reducing the thickness of the glass at the point of fusion of the tubes.

With a stem of the tipless type, made by this method, the inner tube is used as, a combined exhaust tube and arbor. be drawn out of the bulbenters the inner tube from the arbor end, thus making it possible to dispense with the usual located near the stem press. Making the unismall hole after the fires are withdrawn, thereby The air to tary inner tube form both the exhaust tube without buttons, the latter being formed during the inserting operation, it is possible to dispense with arbor-making machines.

A preferred embodiment of the invention is illustrated in the accompanying drawing, in which,

Fig. 1 is a side elevation of my improved stem after fusing the parts together, a portion being shown broken away;

Fig. 2 shows the parts assembledbefore applying heat for using them together;

and Fig. 3 illustrates a section on the line III-III of Fig. 1, on' a largerscale.

In the drawing, 1 re resents-the usual form of flare which is p wed in a suitable fixture. for holding the parts in alignment, with the small end preferably extending downwardly. Thejnner or exhaust tube 2 and conductors or leading-in wires 3 are inserted therein as shown in Fig. 2. The upper portion of the exhaust tube may be held between jaws 10 and 11, the flare tube between jaws 12 and 13 and thelower portion of the exhaust tube between jaws I4 and15.

4o V withdrawn from the bulb through a smal The lower end of the exhaust tube may be closed by a suitable socket 16 which may be of soft rubber or other material and air may be directed down thecexhaust tube from any suitable supply line through a nozzle 17 Heat, preferably in the form of gas fires 18 and 19, is applied to soften the lower or smaller end 21 of the flare and the adjacent portion of the exhaust -tube until the flare contracts about the inner tube because of the causes the same to expand slightly a ainst.

the contracted portion of the flare, as s own at 4, thereby welding the tube and flare together perfectly and also making a perfect seal between the wires and the glass, as .shown in Figs. 1 and 3. The air jet may be continued until the glass in the seal solid fies,

thereby reducing the usual strains, by cooling more uniformly.

will readily beseen that, by this method, the stem includes but two pieces of glass, namely, The usualcane glass arbor is therefore dispensed with, as well as the o eration of press-.

mg the glass around the lea ing-in wires and.

of consolidating the flare, the exhaust tube and the arbor. In addition, the portion of the inner or exhaust tube, shown in the, drawing, downwardly frojecting below the seal forms the, arbor and if desired, may have formed thereon one or more buttons.

In exhausting a bulb formed with a stem of this character, theair, insteadof bein hole formed near the flare or near the stem press, as in former types of tipless stem con-- struction, is withdrawn through the inner tube forming the arbor. This inner or exhaust Ytube, therefore, forms the arbor in addition to its usual obviates handling three pieces of glass per stein.

In makinga stemfor a lamp of the tipped variety, the usual solid cane arbor may; be used andboth the inner tube and the jet of air are unnecessary. The seal in this case is formed'inmuch the usual manner, up to omitted. In the p tion hasbeen considered essential. Although this invention is shown embodv applications of its principles arev contem- 'plated,'as, for instance, in anyelectrical device. employing a vitreous container. It willother electrodes'in' glass withoutthe applithe flare and the inner tube..

' portions of the. 'wallsof function and thereby.

led in a'stem for-an incandescent lamp, other.

.tions having a bulbous rea er? cation of mechanical force, is of general utility. V

sider to be the preferred embodiment of my invention, it is to be understood that many changes may be effected therein and that my invention is to be limited only by the scope of the appended claims.

What is claimed is '1. The method of making incandescent While I have illustrated what I new conly small diameter and a relatively large diameter glass tube which comprises supporting the tubes initially spaced apart and substantially in concentric relation, heating to fuse an end ofthe outer tube to contract the same about the inner tube and supplying suflicient heat to fuse the inner tube and expandin the fused portions of both the tubes to intlmatel unite them.

2. The method of mali ing incandescent electric lamp stems composed of a relatively small diameter and a relatively large diam-' eter. glass tube which comprises supporting the tubes initially spaced apart and substantially in concentric relation, disposing leading-in wires between the tubes, heating to fuse an end of the outer tube to contract the same about the inner tube and suppl ing sufiicient heat to fuse the inner tube an panding both the fused portions of the tubes to intimately unite them.

3. A stem for an incandescent electric lamp eomprising a relatively small diameter exhaust tube and a relatively large diameter flare tube, portions of the walls of said tubes being united to constitute a single wall and enlargedto bulbous form interiorly and exteriorly to provide relatively'lar e united portions of said exhaust tube and are tube.

4. A stem for an incandescent electric lamp or other sealed device comprising an exhaust tube of relative] small diameter and a flare tube of relatively large diameter, 'said tubes being united and having their united portions shaped to bulbous form interiorly and exteriorly andhaving a common wall.

5.-A stem for an incandescent electric lamp or other sealed device, comprising an exhausttube and a flare tube concentrically arranged and having one end of the flare tube fused to the exhaust tube and shaped to bulbous form both interi'orly and exteriorl the point of mechanical pressing, which is 1 ast this pressing opera-- 6. A stem for' an incandescent electric lamp or other sealed device-comprising'an exhaust tube and a flare tube'concentrically arranged, leading-in wires disposed between 7 the flare tube being a flare tubeof relatively large diameter and 75 electriclamp stems composed of a relati veeeaew an exhaust tube of relatively small diameter which comprises placing the flare tube around the exhaust tube, disposing leadingin wires inthe space between the tubes, applying heat to one end of the flare tube to constrict the same about the exhaust tube whereby the surface tension of the flare tube when nearly molten causes it to contract around the exhaust tube and become fused thereto, maintaining sufiicient heat to render the contacting portions of the exhaust tube and flare tube plastic and in applying fluid pressure to work the fused mass and consolidate the tubes with the leading-in wires embedded in the fused portion.

8. The method of making tipless incandescent lamp stems which initially include a flare tube of relatively large diameter and an exhaust tube of relatively small diameter, a

which comprises placing the around the exhaust tube, applying heat to one end of the flare tube, constrict the same about the exhaust tube and permitting the surface tension of the flare when nearly molten to contract around the exhaust tube and unite thereto, maintaining the application of heat to render the flare tube and the contacting portion of the exhaust tube plastic and in applying fluid pressure to expand the heated portions of the tube united in a common wall to attain an eflective union of the tubes.

In testimony whereof, I have hereunto subscribed my name this 24th day of March,

i J OHN JOSEPH HIGGINS.

flare tube 

